For many years, it has been well known that the fresh taste and quality of fruit and vegetables can be preserved in reasonably good condition for extended periods of time by keeping the fruit and vegetables in chilled or refrigerated condition. When fresh fruits and vegetables are shipped from the source to the consuming marketplace, it has been customary for many years to pack the chilled fruit and vegetables in ice, or some other chilling medium. A problem with ice is that when it thaws, it converts to water, which can be a nuisance and often causes water damage.
In recent years, it has become the practice to utilize cooling packs of gel as an alternative to ice. Such cooling packs are used for chilling fruits and vegetables and also for treatment of sports injuries. A number of patents have issued in recent years directed to various designs of alternative cooling packs.
U.S. Pat. No. 3,802,220, granted Apr. 9, 1974, Pompo, assigned to Cool-Pack Corp., discloses a cooling pack constructed of a quilt-like sheet comprising two layers of polyethylene defining a plurality of small containers joined together through bonded container boundary zones, each container serving as a cooling cushion by reason of being filled with a pre-cooled stiff gel which has not frozen rigid, but which has a gel-like temperature range of at least 30.degree. F., desirably about 60.degree. F. Each such flexible container not only provides cooling but it can provide some cushioning and protection from impact. The composition of the gel has a rigid freezing point lower than about -40.degree. F., desirably lower than -60.degree. F., and consists of a mixture of 20 to 55 percent by weight amide of an acid having a molecular weight of at least 200, from 30 to 65 percent by weight of an organic water-miscible liquid having at least one hydroxyl group and a molecular weight less than 100, and from 15 to 50 percent by weight of water. The cushions can also have other shapes.
U.S. Pat. No. 4,311,022, issued Jan. 19, 1982, Hall, discloses an ice pack which is constructed of a plurality of separate compartments which are connected together through a webbing assembly. Each of the compartments is movable in respect to each other thereby permitting the ice pack to be located within confined various sizes of spaces. Each compartment of the ice pack contains a quantity of freezable substance which is used as a refrigerant. Each compartment is enclosed by a wall assembly which retards the accumulation of moisture on the exterior surface of the wall assembly.
U.S. Pat. No. 4,556,055, issued Dec. 3, 1985, Bonner, Jr., discloses a cold compress bandage defined by a layer of closed cell foam polymeric material sandwiched between and bonded to adjacent layers of fabric. One of the layers of fabric is absorbent with respect to aqueous liquids and is adapted to be in contact with an area of the body. A plurality of straps are releasably attached to the bandage to form a compress. The straps facilitate adjustment of the compress. Optionally, a plurality of elongated pockets may be sewn to the fabric layer opposite the absorbent layer for insertion of straps to form a brace or provide for additional cooling. Electrodes may be incorporated into the bandage to provide electrical stimulation.
U.S. Pat. No. 4,908,248, issued Mar. 13, 1990, Nakashima et al., discloses a cooling pack for cooling objects in the proximity thereof. The cooling pack consists of a single pouch or a plurality of continuous pouches, wherein each pouch has at least one face being made of water-permeable material and has sealed therein a hygroscopically swelling material. The sealed material of the cooling device before being chilled in a freezer or freezing compartment is not hygroscopically swelled and is not voluminous so that it can be decreased in weight by reducing the quantity of the sealed material which can improve the transportation efficiency, thereby resulting in lowered transportation costs. Furthermore, the device can be easily and securely attached to any body part or object such as the shoulder of a man or a beer bottle.
U.S. Pat. No. 5,135,787, issued Aug. 4, 1992, Bair, discloses an iced food shipping container and a novel aqueous liquid absorbing pad for use therein. The pad comprises superabsorbing polymer particles distributed in a polyester carded web contained between hydrophillic fabric outer layers. The pad can absorb more than 100 times its dry weight in water and other aqueous liquids that form during iced food shipment.
U.S. Pat. No. 5,150,707, issued Sep. 29, 1992, Anderson, discloses a thermal pack having a high heat-retention character, which may be quickly heated or chilled. The pack consists of an absorbent package having a gel-forming synthetic organic resin in particulate form deposited on an adhesive-coated substrate disposed between a pair of fibrous non-woven porous filter layers and covered on the outside by a pair of paper-like plies of non-woven porous absorbent material. The outside covers are seamed together around their periphery to form a closed envelope. The thermal pack may be positioned in a pouch which is adapted to be held in place over the afflicted area of the body by releasable fastening means. The pack and pouch are formed of a porous material which is capable of being heated in a microwave oven or cooled in a freezer. In making the absorbent pack, a predetermined quantity of particulate gel-forming resinous material is deposited on the adhesive surface of the substrate, which is water-soluble so that in use, when the assembly is immersed in water, the gel-forming synthetic organic resinous material is free to expand as a gel and fill the envelope provided by the peripheral seaming.
U.S. Pat. No. 5,391,198, issued Feb. 21, 1995, Cheney, III, et al., discloses a reusable compress and a method of applying heat or cold to human or animal parts. The method involves saturating crystals of a water soluble acrylic polymer and a thickening agent through the porous fabric of the compress bag containing the acrylic polymer and the thickener. The compress is heated in warm water or a microwave oven or cooled in a cool environment such as a freezer. The compress is applied to a human or animal part to warm or cool the body part. When the compress is no longer needed, the gel is de-hydrated and the compress is easily stored for safe reuse.
U.S. Pat. No. 5,649,409, granted Jul. 22, 1997, Gujer et al., assigned to Thermarite Pty. Ltd., discloses an apparatus for manufacturing a flexible container which has particulate material located between two flexible web members. The apparatus comprises a first feed means suitably in the form of one or more drive roller assemblies for advancing a first flexible web member through the apparatus. A metering means suitably in the form of a metering roller having recesses on its peripheral face accommodates the particulate material and deposits the particulate material onto the first flexible web member. A second feed means suitably in the form of a roller assembly passes a second flexible web member over the first flexible web member containing the particulate material. A sealing means suitably comprising a roller assembly having one of the rollers including heated zones or portions along its external surface seals the first and second web members as they pass between the rollers. The web members are sealed together along areas corresponding to contact of the web members with the heated zones or portions. Using the apparatus, there can be formed flexible containers or sachets containing particulate material such as super absorbent polymer which can be immersed in water and subsequently frozen to be used as a heat exchange pad.